Electron-induced chemistry in microhydrated sulfuric acid clusters

0482678 - ÚFCH JH 2018 RIV DE eng J - Journal Article
Lengyel, Jozef - Pysanenko, Andriy - Fárník, Michal
Electron-induced chemistry in microhydrated sulfuric acid clusters.
Atmospheric Chemistry and Physics. Roč. 17, č. 22 (2017), s. 14171-14180. ISSN 1680-7316. E-ISSN 1680-7324
R&D Projects: GA ČR(CZ) GA17-04068S
Grant - others:Austrian Science Fund (FWF)(AT) M1983-N34
Institutional support: RVO:61388955
Keywords : induced aerosol formation * particle formation * atmospheric implication
OECD category: Physical chemistry
Impact factor: 5.509, year: 2017
Method of publishing: Open access

We investigate the mixed sulfuric acid-water clusters in a molecular beam experiment with electron attachment and negative ion mass spectrometry and complement the experiment by density functional theory (DFT) calculations. The microhydration of (H2SO4)(m)(H2O)(n) clusters is controlled by the expansion conditions, and the electron attachment yields the main cluster ion series (H2SO4)(m)(H2O)(n)HSO4- and (H2O)(n)H2SO4-. The mass spectra provide an experimental evidence for the onset of the ionic dissociation of sulfuric acid and ion-pair (HSO4-center dot center dot center dot H3O+) formation in the neutral H2SO4(H2O)(n) clusters with n >= 5 water molecules, in excellent agreement with the theoretical predictions. In the clusters with two sulfuric acid molecules (H2SO4)(2)(H2O)(n) this process starts as early as n >= 2 water molecules. The (H2SO4)(m) (H2O)(n)HSO4 clusters are formed after the dissociative electron attachment to the clusters containing the (HSO4-center dot center dot center dot H3O+) ion-pair structure, which leads to the electron recombination with the H3O+ moiety generating H2O molecule and the H-atom dissociation from the cluster. The (H2O)(n) H2SO4- cluster ions point to an efficient caging of the H-atom by the surrounding water molecules. The electron-energy dependencies exhibit an efficient electron attachment at low electron energies below 3 eV, and no resonances above this energy, for all the measured mass peaks. This shows that in the atmospheric chemistry only the low-energy electrons can be efficiently captured by the sulfuric acid-water clusters and converted into the negative ions. Possible atmospheric consequences of the acidic dissociation in the clusters and the electron attachment to the sulfuric acid-water aerosols are discussed.
Permanent Link: http://hdl.handle.net/11104/0278094